Análise da viabilidade do reuso de água cinza para produção de argamassa: um estudo das propriedades mecânicas, químicas e microbiológicas

Abstract

Brazil has 14% of the world's drinking water, however, water scarcity has become an increasingly frequent problem in the country, especially in the Brazilian semi-arid regions. Because of this, it is important to look for alternatives that reduce the consumption of drinking water in activities that do not require this high-quality resource. The present study seeks to evaluate the reuse of gray water (AC) for the production of mortars, using blends of 50 and 25% AC. The Test Bodies (CP) produced were characterized by mechanical, chemical, microstructural and microbiological tests. The results obtained for the mechanical resistance at 28 days of the AC blends were satisfactory, presenting compressive strengths above 8 MPa, being classified as P6, and tensile strength above 3 MPa, being classified as R6, according to NBR 13281/05. The study of the specific surface area, carried out using the BET method, showed the following specific area values: 2.5 m2/g found for 50% AC and 2.02 m2/g for 25% AC. The study carried out by FTIR exhibited the following functional groups characteristic of the mortar: 780 cm-1 (Al-O), 530 and 459 cm-1 (Si-O) and 3440 cm-1 (O-H). Through the changes found in the peak at 780 cm-1 (Al-O), for the mortars studied, it was possible to verify a limit zone for the use of AC in the mortar, which was 50% AC. The bacteriological study of CPs 25 and 50% AC carried out after 7 days of curing showed a positive result for total coliforms and a negative result for E. coli. After 28 days of curing, all bacteriological tests were negative. The test for the presence of fungi also showed a negative result, showing that the blends are a safe alternative in terms of microbiological contaminants. Thus, it can be concluded that the use of gray water in blends of 25 and 50% AC in kneading is viable and can be an important resource in construction.